BOLT 8T9101 - Caterpillar

The vibration damper is installed on the front of the crankshaft. There is one type of hub assembly that can be installed to this engine. The vibration damper is installed in order to help remove torsional vibration in the engine.
Illustration 1 g01623217
Vibration damper with hub assembly (1) Crankshaft adapter (2) Pulley (3) Vibration damper (4) Setscrews (5) BracketReplace the vibration damper if any of the following conditions exist:
There is any impact damage to the outer casing.
There is leakage of the viscous fluid from the cover plate.
There is movement of the pulley or the outer ring on the hub.
There is a large amount of gear train wear that is not caused by lack of oil.
Analysis of the engine oil has revealed that the front main bearing is badly worn.
The engine has had a failure because of a broken crankshaft.Check the areas around the holes for the bolts in the vibration damper for cracks or for wear and for damage.Use the following steps in order to check the alignment and the runout of the vibration damper:
Remove any debris from the front face of the vibration damper. Remove any debris from the circumference of the vibration damper.
Mount the dial indicator on the front cover. Use the dial indicator to measure the outer face of the vibration damper. Set the dial indicator to read 0.00 mm (0.00 inch).
Rotate the crankshaft at intervals of 45 degrees and read the dial indicator.
The difference between the lower measurements and the higher measurements that are read on the dial indicator at all four points must not be more than 0.18 mm (0.007 inch).If the reading on the dial indicator is more than 0.18 mm (0.007 inch), inspect the pulley and the vibration damper for damage. If the pulley or the vibration damper are damaged, use new parts for replacement.
Move the dial indicator so that the dial indicator will measure the circumference of the vibration damper. Set the dial indicator to read 0.00 mm (0.00 inch).
Slowly rotate the crankshaft in order to measure the runout of the circumference of the vibration damper. Use the highest reading and the lowest reading on the dial indicator. The maximum and the minimum readings on the dial indicator should not vary more than 0.12 mm (0.005 inch).If the reading on the dial indicator is more than 0.12 mm (0.005 inch), inspect the pulley and the vibration damper for damage. If the pulley or the vibration damper are damaged, use new parts for replacement.